The Department of Homeland Security (DHS) has seen its influence and power expand under President Trump, whose efforts to bolster border security and crack down on illegal immigration have run through the youngest federal department.

Homeland Security, established just 15 years ago after the Sept. 11 attacks, has enjoyed greater visibility and influence as Trump has pledged to establish "law and order" and build a wall at the southern border.

The department has been given the lead on implementing Trump's most controversial and prominent policy moves, including the president's executive orders barring certain travelers from entering the country.

Homeland Security agents have also cracked down on illegal immigration and so-called sanctuary cities, arresting nearly 500 undocumented immigrants in areas refusing to comply with Trump's deportation efforts last month.